DIVISION OF COLLAR-CELLS OF CALCAREA HETEROCCELA. 131 
apex, and though usually spherical, may sometimes be slightly, 
drawn out towards the top of the cell. The blepharoplast is 
a small granule staining intensely with iron-haematoxy lin ; 
with iron-hasmatein it shows quite sharply, but is pale grey 
in colour, while the chromatin of the nucleus is a blueisli- 
black; with Twort’s stain it is not very readily visible, but 
whenever it can be made out it is always of the cytoplasmic 
colour, namely, green (fig. 28). There is no shred of evidence 
in the staining reaction to suggest that the structure in 
question is of a chromatic or nuclear nature. To insist on 
the achromatic nature of a centrosome (as in effect the 
blepharoplast of a collar-cell really is) at the present date 
seems a useless waste of energ} 7 and almost an anachronism, 
were it not for the recent theories of such well-known workers 
as Hartmann and Prowazek (2a). The centrosome-blepharo- 
plast. is situated at the extreme upper edge of the protoplasmic 
body, and is connected, as has already been said, with the 
nucleus by a double rhizoplast. Iu many cases the double 
nature of this last structure escapes observation, the two 
strands lying very closely side by side. It is, however, 
obvious from a careful study of a sufficiently large number of 
cells that two strands (sometimes widely separated from each 
other and forming a triangle as in figs. 3 and 5) and not one 
only connect the blepharoplast with the nucleus. This 
rhizoplast persists throughout the whole life of the cell except, 
as will be seen hereafter, for a very short period immediately 
before division. From the blepharoplast arises the flagellum, 
which is of considerable length and extends beyond the 
collar. 
To talk of the nucleus of any living and functioning cell 
as being in the resting state is a self-contradictory phrase 
which cytologists are only gradually abandoning. In the 
collar-cells the variety of appearance in the nucleus of the 
non-dividing cells is particularly striking. I ufortunately 
from the nature of the case one is unable to correlate the 
physiological state and the particular appearance of the 
nucleus, and of the distribution of the chromatin, etc., within 
